Merge bitcoin#14517: qt: Fix start with the -min option

9300961 Fix start with the `-min` option (Hennadii Stepanov)

Pull request description:

  From IRC:

  > 2018-10-17T12:36:38  \<Drakon\> The option to minimize to system tray instead of the taskbar ist available, but doesn't have an effect if it is started with the -min option. If I start it via that option, I have to click on the program symbil on the taskbar and then minimize it again in order to get it minimized to system tray.
  > 2018-10-17T12:37:28  \<Drakon\> That's annoying.
  > 2018-10-17T13:51:19  \<wumpus\> can you open an issue for that please? https://github.com/bitcoin/bitcoin/issues/new
  > 2018-10-17T13:53:24  \<wumpus\> (if there isn't one yet-)

  This PR fixes this bug.

Tree-SHA512: c5a5521287b49b13859edc7c6bd1cd07cac14b84740450181dce00bf2781fc3dfc84476794baa16b0e26a2d004164617afdb61f829e629569703c5bcc45e2a4e

src/qt/bitcoin.cpp

@@ -392,14 +392,13 @@ void BitcoinApplication::initializeResult(bool success)
         }
 #endif
 
-        // If -min option passed, start window minimized.
-        if(gArgs.GetBoolArg("-min", false))
-        {
-            window->showMinimized();
-        }
-        else
-        {
+        // If -min option passed, start window minimized (iconified) or minimized to tray
+        if (!gArgs.GetBoolArg("-min", false)) {
             window->show();
+        } else if (clientModel->getOptionsModel()->getMinimizeToTray() && window->hasTrayIcon()) {
+            // do nothing as the window is managed by the tray icon
+        } else {
+            window->showMinimized();
         }
         Q_EMIT splashFinished();
         Q_EMIT windowShown(window);

src/qt/bitcoingui.h

@@ -86,6 +86,11 @@ class BitcoinGUI : public QMainWindow
 #endif // ENABLE_WALLET
     bool enableWallet = false;
 
+    /** Get the tray icon status.
+        Some systems have not "system tray" or "notification area" available.
+    */
+    bool hasTrayIcon() const { return trayIcon; }
+
 protected:
     void changeEvent(QEvent *e);
     void closeEvent(QCloseEvent *event);